this is fucking awesome effort. well done dude!
i been watching Roarockit videos this evening to learn the method so my Dad and I can start one together, and doing the size you’ve done with the battery channels etc seems like a monster task.
The Rocket | 4wd hummies hubs | 4x chaka vesc | 10s4p LG HE2 li-ion | CNC milled veneer pressed deck
Thanks, it’s a lot of work pressing the sheets, especially getting the air out of the bag. Check you seal consistently. I had it break a few times, the worst being the lid as I stayed for 2 hours, left, came back 8 hours later and found the seal failed. It does happen, and if you catch it, press the seal again a few times, and it’ll only take a few pumps to get back to good pressure. It doesn’t completely fail, but you’ll notice that black mesh is just a bit lose. That was the first sign I picked up on, then around the edges was a little loose. Again, it was so minor, that it could be fixed with like 5 pumps (and it takes like 600 pumps or more to press it once you seal it after gluing), so keep a close eye on it. The first 2 hours are the most important, but you want it in there for 24 hours under max pressure, or it won’t be prefect.
Roar rocket actually gave me the idea with their pre-cut kits. I figured if they sell kits for pre cut boards, why can’t I pre cut them with channels with my cnc milling machine and glue them, like one of their kits. And it worked great.
Just to make the deck though, I probably spent more than 200 hours total. It took 2 months of time, cutting and gluing at least 5 days a week, sometimes more. Most of that time was the steep learning curve of making such a deck, so I could make it faster again, but it will still takes me a minimum of 30 hours to make 1 deck in 1 on 1 with the board time, more when you consider it takes 5 days to glue it all the way.
The other interesting thing is I just did my first full discharge and recharge, and the cells when discharged became slightly unbalanced, but charged up, I was able to let the charger stop. packs at 42.02. The highest cell is 4.202. the lowest is 4.185. Which was what I was at before the full discharge, so a BMS in this particular discharge and charge cycle would have been completely useless, and done nothing.
NO BMS FTW!!!
Yeah thats weird that you would have so much difference between the watt meter and the VESC. You should get a trust worthy voltage meter and set it at measuring amperage and have the board just on a table where they only draw around 5A with the wheels free spinning and see which is right, the VESC or the watt meter compared to the accurate voltage meter.
Yea, I need to do more tests, get to the bottom of it, and figure this out. But I know it can’t be that high, because in my test today, I started at 41.7v and ended with 37.6v. I have my vescs set to slow cutoff at 33v, hard cutoff at 32v (just in case cells become unbalanced and I don’t have time to balance them. In this test, I did a 4 mile run involving 9 blocks of steep uphills, 9 steep downs, most moderate ups or downs, and a few flat. I am willing to bet I could have done 6-7 miles in these harsh extremely hilly conditions at full throttle (cause that’s all I ever ride at). If I did my distance tests right, I could easily milk 15-20 miles. On flats, 12+ miles. But this is why I hate max range numbers. This and they don’t account for rider weight. If I take a 120 pound rider and give them a flat and downhill route, 20 miles no questions asked. Me being 200 pounds, its almost double the weight, so I would expect 10 miles. Companies never state how they come up with their range numbers, and I feel like some do just what I said to bullshit their numbers.
Also I thought you mentioned something about needing a switch for your board? I have a thread about a couple different switches I designed and I uploaded all the schematics and places to buy the components on there as well so you can build your own. I also sell them for $25-$35 if you dont feel comfortable making one yourself if your interested. THREAD
Can do you an 80 amp version?
Yeah I could though like I said it would be overkill and I think my 60A dual 7530 version would be completely suitable because of its peak at 760A. I could do an 80A version with two IRFB7530-7P though that would be more like $40-45 because I would have to order like 10 of them from Mouser. Though I could definitely do it.
I might try it some time in the near future. I need to find out what amps I really am running. And I got the dyi switch in the mail today. So I’m going to hook it up tomorrow and see how it goes.
Alright good to hear and I hope whatever you do works.
Im open ideas of how to improve on my designs. I want to get the production of this board to a place where I can fesebly make 20 of these boards to start with. And your switchs look very simple, yet effective. I’m always interested in simple.
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Cells generally become more and more unbalanced over time. Check again after using it for a couple months to see the deviation.
And that would explain a lot. My cells actually became more balanced today without balance charging and I full drained twice today.
Yeah its about as simple as they come lol. Now it isnt perfect because there is still some drain leakage though it is incredibly low and for EBoards its pretty much irrelevant. For example when the switch is plugged in and in the off state a small amount of current is let through the switch though its so low that I had my board sitting around “down for repairs” for over a month and the battery voltage never went below what it was at before, ~3…8V per cell for “storage”. Anyways its very simple and works pretty damn well and ive used it for many other applications not only my EBoard but other high current applications, like my lab bench PSU that has a similar MOSFET switch using a 3034 fet instead. And if your ever interested in ordering in small bulk like 10-20 contact me and ill see if I could do it, though no guarantees, remember im just a single person compared to other groups like Enertion, DIY, etc. Also if you were ever planning on selling your boards like making the 20 of them like you stated I would highly recommend that you use a BMS just for ease of use to consumers, maybe talk to @longhairedboy and see what he has to say about it cause he is always using BMS’s.
This is so sick. So, so sick. and it gives me ideas.
So you were saying you were riding with laptop connected to the board and re cording your screen to measure the results right? Does the VESC interface over USB or what port do you use to get readings off of it. I was thinking you could have some sort of Arduino connected to it 're cording the information an SD card so you can look at it later on. I might actually look into some thing like this in the future though I would have to know a lot more about the VESC in the first place.
I rode my last build, which was my back 2 motors and vescs, and same battery minus 1 p (so 10s3p, same cells), with my laptop running the bldc program recording the screen of the active sampling. Its sketchy to say the least, because I have to keep a cable connected via the usb port on the vesc. I have to keep it in one hand while I control the board with the other, and i’m 6’ 1", and the cables like, 3 feet long. So not something II look forward to doing again, but I need to get a look at whats happening.
I want to write code for the vesc, but I wish vedder documented his code better. There’s not a lot of info of whats where, how he decided to split different things up, even what these variables mean, as looking through the code, he named some variables likes like gstd (don’t know if that’s a real variable name, but my point is some are just abbreviations I simply don’t know). I need to spend a lot of time and ask vedder a lot of questions before I can try to write anything. It’ll help to learn actual C this semester too, I know objective-c and c++.
ahhh, programmers… 
Here’s a quick video of hummie riding it up a 3% grade hill. Not much, and it doesn’t show the torque, but more videos to come…
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uhm, i dont get your balance issues - 4.2 vs 4.185 is already a pretty significant difference in my books. my batteries never showed any of that kind of drift, not even my very first 1.5yo evolve battery. youll have to use a charger with adjustable end of charge voltage. 